The present invention relates to a location updating system in a mobile communication system and, in particular, relates to such a system in which a paging area where a mobile station is located is registered in a fixed network.
In a cellular mobile communication system, the service area for mobile communication is covered with a plurality of location registration areas, and each of the location registration area has a plurality of zones each of which has a base station having a transceiver.
When a mobile station moves beyond the border of a location registration area, the location code or the location identifier of the mobile station is updated so that the updated code relates to the location registration area where the mobile station is currently registered. The location updating operation is carried out through the broadcast information by a fixed network. The fixed network has a home memory which has information about which location registration area each mobile station is currently registered in.
When a fixed network calls a mobile station, the fixed network transmits a paging signal to a mobile station through a plurality of base stations which belong to a location registration area where the mobile station is currently registered, so that the connection with the mobile station is established.
Conventionally, the structure of a location registration area has been common for all the mobile stations. In such system, when subscriber density increases, and each cell becomes smaller, the traffic for location updating control occupies a large fraction in a control channel, and it becomes larger than the traffic for connection control.
Conventionally, the size of a location registration area has been determined so that the ratio of the location updating traffic at the zone at the peripheral of the location registration area and the paging traffic for connection control is optimized.
However, when a location registration area is determined, a zone except a peripheral zone in a location registration area must have almost the same number of control channels as that in a peripheral zone, because of downstream paging channel, in spite of surplus upstream channels for location updating.
Therefore, prior art which has a common location registration area has the disadvantages that the frequency band is not used effectively, and that a large number of transceivers for control channels must be installed.